🇩🇪 enterJS 2024

Web performance APIs you (probably) didn't know existed

Responsiveness to interaction is crucial for our apps and you’ve probably heard about the amazing tools we have to measure web performance. But did you know there are many performance APIs native to the Web Platform?

In this talk, we’ll see how to leverage the power of some of them to reliably measure responsiveness and correctly identify culprits for bad experiences.

1. Hello, enterJS 👋 🇩🇪 WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED • MAY 8, 2024.
2. WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED MATHEUS ALBUQUERQUE • @ythecombinator
3. Matheus Albuquerque ↝ 𝕏 ythecombinator ↝ 👨💻 Sr. SWE @ Medallia ↝ ⚡ Google Developer Expert ↝ ⚛ PC @ React Su m m it NYC ↝ 🧑🏫 Mentor @ TechLabs
4. Matheus Albuquerque ↝ 𝕏 ythecombinator ↝ 👨💻 Sr. SWE @ Medallia ↝ ⚡ Google Developer Expert ↝ ⚛ PC @ React Su m m it NYC ↝ 🧑🏫 Mentor @ TechLabs ↑ ALL THE LINKS!
5. Why am I here? WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED
6. WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED MATHEUS ALBUQUERQUE • @ythecombinator
7. MATHEUS ALBUQUERQUE • @ythecombinator WEB PERFORMANCE STUFF YOU ALREADY KNOW
8. YOU ALREADY KNOW… ↝ HTTP/2 ↝ COMPRESS JAVASCRIPT (E.G. WITH BROTLI/ZSTD) AND USE IMAGE CDNS (40–80% SAVINGS) ↝ OPTIMIZE THIRD-PARTIES (DEFER/REPLACE/UPDATE THEM) ↝ WORKERS TO OFF-LOAD THE MAIN THREAD
9. YOU ALREADY KNOW… — HTTPS://WWW.PATTERNS.DEV
10. Å
11. FIXING WEB PERFORMANCE
12. FIXING WEB PERFORMANCE
13. This talk presents Why am I here? Measuring Measuring (with the platform) Optimizing (with the platform) Why are we here? Closing thoughts
14. This talk presents Why am I here? Measuring Measuring (with the platform) Optimizing (with the platform) Why are we here? Closing thoughts
15. Measuring WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED
16. #QUESTION 🤔 What does it mean to be fast?
17. #QUESTION 🤔 What does it mean to be fast? If you were to summarize web performance in one metric, what’d be your pick?
18. #QUESTION 🤔 What does it mean to be fast? If you were to summarize web performance in one metric, what’d be your pick? e.g. load time, responsiveness, etc.
20. Å
21. #PROTIP💡 A lot of loading metrics don't capture user experience. We need to think about our metrics in terms of what matters.
22. #QUESTION 🤔 What does it mean to be fast? If you were to summarize web performance in one metric, what’d be your pick?
23. WHAT DOES IT MEAN TO BE FAST?
24. #PROTIP💡 Load metrics are not a single number.
25. WHAT DOES IT MEAN TO BE FAST? PERCEIVED LOAD SPEED HOW QUICKLY A PAGE CAN LOAD AND RENDER ALL OF ITS VISUAL ELEMENTS TO THE SCREEN LOAD RESPONSIVENESS HOW QUICKLY A PAGE CAN LOAD/RUN ANY REQUIRED JS IN ORDER FOR COMPONENTS TO RESPOND TO USER INTERACTION RUNTIME RESPONSIVENESS AFTER THE PAGE LOAD, HOW QUICKLY CAN THE PAGE RESPOND TO USER INTERACTION? SMOOTHNESS DO TRANSITIONS & ANIMATIONS RENDER AT A CONSISTENT FRAME RATE AND FLOW FLUIDLY?
26. #PROTIP💡 The only way to truly know how your site performs for your users is to actually measure its performance as those users are loading and interacting with it.
27. WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED Jean-Antoine Nollet
28. JEAN-ANTOINE NOLLET ↝ THE FIRST EVER RUM EXPERIMENT IN 1746 ↝ HE GATHERED ˜200 MONKS IN CIRCUMFERENCE, WIRED USING IRON, AND DISCHARGED A BATTERY THROUGH THE HUMAN CHAIN ↝ HE WAS TESTING THE LATENCY OF AN ELECTRIC SIGNAL WITH REAL USERS
29. #PROTIP💡 Browsers now provide us with many apis to fetch performance metrics that help site owners make sites faster.
30. WEB PERFORMANCE STUFF YOU ALREADY KNOW MATHEUS ALBUQUERQUE • @ythecombinator
31. WEB PLATFORM PERF APIS I DIDN’T KNOW EXISTED MATHEUS ALBUQUERQUE • @ythecombinator
32. Measuring with the platform WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED
33. MEASUREMENT APIS GENERAL STUFF DOMHighResTimeStamp, PerformanceObserver, PAGE VISIBILITY API & LAYOUT INSTABILITY API PROFILING LONG TASKS API, UserAgentSpecificMemory & JS SELF- PROFILING API TIMING USER TIMING, ELEMENT TIMING. EVENT TIMING, RESOURCE TIMING, NAVIGATION TIMING & SERVER TIMING SENSORS BATTERY STATUS & NETWORK INFORMATION
34. #1 PAGE VISIBILITY document.hidden; document.visibilityState; document.addEventListener("visibilitychange",() = > { if(document.visibilityState==="hidden"){ console.log("This window is hidden") } else{ console.log("This window is visible") } })
35. #1 PAGE VISIBILITY ↝ CANCEL NETWORK REQUESTS AND OTHER TIME-BASED EVENTS ↝ FETCH INCOMPLETE MEDIA OR DOWNLOAD THE REST OF YOUR BUNDLES USING DYNAMIC IMPORTS ↝ PAUSE VIDEOS AND CAROUSELS, IF THE USER IS NOT WATCHING THEM
36. #2 PerformanceObserver ↝ SUBSCRIBE TO PERFORMANCE-RELATED EVENTS ↝ CALLBACKS ARE GENERALLY FIRED DURING IDLE PERIODS ↝ YOU TELL THE OBSERVER WHAT TYPES OF ENTRIES TO LISTEN FOR
37. #2 PerformanceObserver const observer = new PerformanceObserver((list) = > { for (const entry of list.getEntries()) { console.log(entry.toJSON()); } }); observer.observe({type: 'some-entry-type'});
38. #3 LAYOUT INSTABILITY ↝ MANY WEBSITES HAVE DOM ELEMENTS SHIFTING AROUND DUE TO CONTENT LOADING ASYNCHRONOUSLY ↝ THIS API GIVES US A LIST OF ALL LAYOUT SHIFT EVENTS ON A PAGE
39. #3 LAYOUT INSTABILITY const observer = new PerformanceObserver((list) = > { const entries = list.getEntries(); / / Shifts that are not preceded by input events const nonInputEntries = entries.filter((entry) = > !entry.hadRecentInput); for (const entry of nonInputEntries) { console.log(entry); } }); observer.observe({type: 'layout-shift'});
40. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
41. #3 LAYOUT INSTABILITY — SPOT
42. #3 LAYOUT INSTABILITY — FIX
43. TIMING — ACT I USER TIMING ALLOWS YOU TO MARK POINTS IN TIME AND THEN MEASURE THE DURATION BETWEEN THOSE MARKS. EVENT TIMING EVENT PROCESSING TIME + TIME UNTIL THE NEXT FRAME CAN BE RENDERED. THE BASIS FOR THE FID METRIC. ELEMENT TIMING MEASURE THE RENDER TIME OF SPECIFIC ELEMENTS. THE BASIS FOR THE LCP METRIC.
44. #1 USER TIMING / / Record the time i m m ediately before running a task performance.mark('myTask:start'); await doMyTask(); / / Record the time i m m ediately after running a task performance.mark('myTask:end'); / / Measure the delta between the start and end of the task performance.measure('myTask', 'myTask:start', ‘myTask:end'); observer.observe({type: 'measure'});
45. #1 USER TIMING
46. #1 USER TIMING — TOOLS — "USER TIMING AND CUSTOM METRICS" BY STEVE SOUDERS
47. #1 USER TIMING — TOOLS — "USER TIMING AND CUSTOM METRICS" BY STEVE SOUDERS — "USER TIMING AND CUSTOM METRICS" BY STEVE SOUDERS
48. #2 ELEMENT TIMING ↝ ALLOWS YOU TO MEASURE THE RENDER TIME OF SPECIFIC ELEMENTS ↝ USEFUL FOR KNOWING WHEN THE LARGEST IMAGE OR TEXT BLOCK WAS PAINTED TO THE SCREEN ↝ THE BASIS FOR THE LARGEST CONTENTFUL PAINT (LCP) METRIC
49. #2 ELEMENT TIMING <img elementtiming="hero-image" /> <p elementtiming="important-paragraph">This is text I care about.</p> observer.observe({type: 'element'});
50. #2 ELEMENT TIMING — TOOLS — "ELEMENT TIMING: ONE TRUE METRIC TO RULE THEM ALL?" BY ANDY DAVIES
51. #2 ELEMENT TIMING ↝ USEFUL TO MEASURE THE EVENT PROCESSING TIME AS WELL AS THE TIME UNTIL THE NEXT FRAME CAN BE RENDERED ↝ EXPOSES A NUMBER OF TIMESTAMPS IN THE EVENT LIFECYCLE ↝ THE BASIS FOR THE FIRST INPUT DELAY METRIC
52. #3 EVENT TIMING const observer = new PerformanceObserver((entryList) = > { const firstInput = entryList.getEntries()[0]; const firstInputDelay = firstInput.processingStart - firstInput.startTime; / / Measure the time it takes to run all event handlers const firstInputProcessingTime = firstInput.processingEnd - firstInput.processingStart; / / Measure the entire duration of the event const firstInputDuration = firstInput.duration; }); observer.observe({type: 'first-input'});
53. #3 EVENT TIMING MEASURE THE LATENCY… ↝ FROM A CLICK UNTIL WE REORDER CONTENT ON A TABLE ↝ TO DRAG A SLIDER TO FILTER SOME DATA ↝ FOR A FLYOUT TO APPEAR WHEN HOVERING A MENU ITEM
54. PROFILING LONG TASKS API REPORTS TASKS THAT TAKES LONGER THAN 50 MS AND IT'S THE BASIS FOR TTI AND TBT METRICS JS SELF-PROFILING API PROFILE SPECIFIC COMPLEX OPERATIONS AND IDENTIFY HOT SPOTS USING A SAMPLING PROFILER UserAgentSpecificMemory DETECT MEMORY LEAKS IN APPS THAT HANDLE A HUGE VOLUME OF DATA
55. #1 LONG TASKS
56. #1 LONG TASKS ↝ REPORTS TASKS THAT TAKES LONGER THAN 50 MS ↝ USEFUL TO TRACK WHEN THE BROWSER'S MAIN THREAD IS BLOCKED ↝ THE BASIS FOR TIME TO INTERACTIVE (TTI) AND TOTAL BLOCKING TIME (TBT) METRICS
57. #1 LONG TASKS
58. #1 LONG TASKS — SPOT observer.observe({type: 'longtask'});
59. #1 LONG TASKS — SPOT observer.observe({type: 'longtask'}); { name: "same-origin-descendant", entryType: "longtask", startTime: 1023.40999995591, duration: 187.19000002602115, attribution: [ { name: "unknown", entryType: "taskattribution", startTime: 0, duration: 0, containerType: "iframe", containerSrc: "child.html", containerId: "", containerName: "child1" } ] };
60. #2 JS SELF - PROFILING const profiler = new Profiler({ sampleInterval: 10, maxBufferSize: 10000 }); / / Do work . . . const trace = await profiler.stop(); sendProfile(trace);
61. #2 JS SELF - PROFILING ↝ PROFILE SPECIFIC COMPLEX OPERATIONS ↝ PROFILE THIRD-PARTY SCRIPTS ↝ COMBINE WITH OTHER EVENTS/IMPORTANT METRICS, LIKE LONG TASKS OR EVENT TIMING APIS
62. #3 UserAgentSpecificMemory ↝ MEASURES THE MEMORY USAGE AND DETECTS MEMORY LEAKS ↝ WAITS FOR THE NEXT GC AND THEN MEASURES MEMORY IMMEDIATELY AFTER THE UNNEEDED MEMORY HAS BEEN RELEASED ↝ FORCES GC IF IT DOES NOT HAPPEN FOR 20S
63. MEMORY LEAKS ↝ FORGETTING TO UNREGISTER AN EVENT LISTENER ↝ ACCIDENTALLY CAPTURING OBJECTS FROM AN IFRAME ↝ NOT CLOSING A WORKER ↝ ACCUMULATING OBJECTS IN ARRAYS
64. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
65. MEMORY LEAKS const obj = { a: new Array(1000), b: new Array(2000) }; setInterval(() = > { console.log(obj.a); }, 1000);
66. #3 UserAgentSpecificMemory performance.measureUserAgentSpecificMemory()
67. { name: "same-origin-descendant", entryType: "longtask", startTime: 1023.40999995591, duration: 187.19000002602115, attribution: [ { name: "unknown", entryType: "taskattribution", startTime: 0, duration: 0, containerType: "iframe", containerSrc: "child.html", containerId: "", containerName: "child1" } ] } { bytes: 1000000, breakdown: [ { bytes: 1000000, attribution: [ { url: "https://example.com", scope: "Window", }, ], types: ["JS", "DOM"], }, { bytes: 0, attribution: [], types: [], }, ], } { "frames": [ { "name": "Profiler" }, { "column": 0, "line": 100, "name": "", "resourceId": 0 }, { "name": "set innerHTML" }, { "column": 10, "line": 10, "name": "A", "resourceId": 1 } { "column": 20, "line": 20, "name": "B", "resourceId": 1 } ], "resources": [ "https://example.com/page", "https://example.com/app.js", ], "samples": [ { "stackId": 0, "timestamp": 161.99500000476837 }, { "stackId": 2, "timestamp": 182.43499994277954 }, { "timestamp": 197.43499994277954 }, { "timestamp": 213.32999992370605 }, { "stackId": 3, "timestamp": 228.59999990463257 }, ], "stacks": [ { "frameId": 0 }, { "frameId": 2 }, { "frameId": 3 }, { "frameId": 4, "parentId": 2 } ] } LONG TASKS SELF-PROFILING USERAGENT MEMORY
68. TIMING — ACT II RESOURCE TIMING RETRIEVE AND ANALYZE DETAILED NETWORK TIMING DATA REGARDING THE LOADING SERVER TIMING COMMUNICATE PERFORMANCE METRICS ABOUT HOW TIME IS SPENT WHILE PROCESSING THE REQUEST NAVIGATION TIMING COMPLETE TIMING INFORMATION FOR NAVIGATION OF A DOCUMENT
69. #1 RESOURCE TIMING const observer = new PerformanceObserver((list) = > { for (const entry of list.getEntries()) { / / If transferSize is 0, the resource was fulfilled via the cache. console.log(entry.name, entry.transferSize === 0); } }); observer.observe({type: 'resource'});
70. #2 NAVIGATION TIMING const observer = new PerformanceObserver((list) = > { for (const entry of list.getEntries()) { console.log('Time to first byte', entry.responseStart); } }); observer.observe({type: 'navigation'});
71. #2 NAVIGATION TIMING
72. #2 NAVIGATION TIMING / / ServiceWorker startup time const workerStartupTime = entry.responseStart - entry.workerStart; / / Request time only (excluding redirects, DNS, and connection/TLS time) const requestTime = entry.responseStart - entry.requestStart; / / Response time only (download) const responseTime = entry.responseEnd - entry.responseStart; / / Request + response time const requestResponseTime = entry.responseEnd - entry.requestStart;
73. #3 SERVER TIMING MEASURE ANY WORK THAT THE SERVER DOES TO COMPLETE A REQUEST: ↝ ROUTING/AUTHENTICATING THE REQUEST ↝ RUNNING CONTENT THROUGH TEMPLATING SYSTEMS ↝ QUERYING DATABASES/API CALLS TO THIRD-PARTY SERVICES
74. #3 SERVER TIMING Server-Timing: database;dur=123;desc="Database", templating;dur=56;desc="Template processing"
75. #3 SERVER TIMING
76. #3 SERVER TIMING
77. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
78. SENSORS BATTERY STATUS INFORMATION ABOUT THE POWER SOURCE, CHARGE LEVEL, AND OTHERS NETWORK INFORMATION ADAPT THE USERS’ EXPERIENCE BASED ON THE QUALITY OF THEIR CONNECTION
79. #1 BATTERY STATUS const batteryInfo = await navigator.getBattery(); batteryInfo.addEventListener("chargingchange", listener); batteryInfo.addEventListener("chargingtimechange", listener); batteryInfo.addEventListener("dischargingtimechange", listener); batteryInfo.addEventListener("levelchange", listener);
80. #2 NETWORK INFORMATION const networkInfo = navigator.connection; navigator.connection.addEventListener('change', onConnectionChange);
81. #2 NETWORK INFORMATION const networkInfo = navigator.connection.addEventListener('change', onConnectionChange); { effectiveType: "4g", rtt: 200, downlink: 1.65, saveData: false, }
82. #2 NETWORK INFORMATION ↝ SWITCH BETWEEN SERVING HIGH/LOW DEFINITION CONTENT BASED ON THE USER'S NETWORK ↝ DECIDE WHETHER TO PRELOAD RESOURCES ↝ DEFER UPLOADS/DOWNLOADS WHEN USERS ARE ON A SLOW CONNECTION ↝ ADAPT TO SITUATIONS WHEN USERS ARE OFFLINE
83. #2 NETWORK INFORMATION switch (connectionType) { case "4g": return <Video src={videoSrc} />; case "3g": return <Image src={imageSrc.hiRes} alt={alt} />; default: return <Image src={imageSrc.lowRes} alt={alt} />; }
84. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
85. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
87. Improving with the platform WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED
88. WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED Resource Hints
89. RESOURCE HINTS ↝ MANY PERFORMANCE OPTIMIZATIONS CAN BE MADE WHEN WE CAN PREDICT WHAT USERS MIGHT DO. ↝ RESOURCE HINTS ARE A SIMPLE BUT EFFECTIVE WAY TO ALLOW DEVELOPERS TO HELP THE BROWSER TO STAY ONE STEP AHEAD OF THE USER AND KEEP PAGES FAST.
90. RESOURCE HINTS < ! - - Preconnect - - > <link rel="preconnect" href="https://fonts.gstatic.com"> <link rel="preconnect" href="https://scripts.example.com"> < ! - - Preloading - - > <link rel="preload" href="https://example.com/fonts/font.woff"> < ! - - DNS Prefetch - - > <link rel="dns-prefetch" href="https://fonts.gstatic.com"> <link rel="dns-prefetch" href="https://images.example.com"> < ! - - Prefetch - - > <link rel="prefetch" href="/uploads/images/pic.png"> <link rel="prefetch" href="https://example.com/news/?page=2"> < ! - - Prerender - - > <link rel="prerender" href="https://example.com/news/?page=2">
91. RESOURCE HINTS < ! - - Preconnect - - > <link rel="preconnect" href="https://fonts.gstatic.com"> <link rel="preconnect" href="https://scripts.example.com"> < ! - - Preloading - - > <link rel="preload" href="https://example.com/fonts/font.woff"> < ! - - DNS Prefetch - - > <link rel="dns-prefetch" href="https://fonts.gstatic.com"> <link rel="dns-prefetch" href="https://images.example.com"> < ! - - Prefetch - - > <link rel="prefetch" href="/uploads/images/pic.png"> <link rel="prefetch" href="https://example.com/news/?page=2"> < ! - - Prerender - - > <link rel="prerender" href="https://example.com/news/?page=2">
92. PRECONNECT ↝ IT ALLOWS THE BROWSER TO SETUP EARLY CONNECTIONS BEFORE THE REQUEST IS ACTUALLY SENT TO THE SERVER. THIS INCLUDES: • TLS NEGOTIATIONS • TCP HANDSHAKES ↝ ELIMINATES ROUNDTRIP LATENCY
93. PRECONNECT 100MS 200MS 300MS 400MS 500MS 600MS 700MS HTML CSS FONT 1 FONT 2 FONTS START LOADING FONTS RENDERED
94. PRECONNECT 100MS 200MS 300MS 400MS 500MS 600MS 700MS HTML CSS FONT 1 FONT 2 FONTS START LOADING FONTS RENDERED FONT 1 FONT 2
95. …AND MUCH MORE! ↝ DNS PREFETCH ⇢ WARNS THE BROWSER ABOUT THE DOMAINS IT’S GOING TO NEED TO LOOK UP ↝ PREFETCH ⇢ FETCH RESOURCES IN THE BACKGROUND AND STORE THEM IN CACHE ↝ PRERENDER ⇢ IT GOES ONE STEP FURTHER AND EXECUTES THE FILES
96. WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED Priority Hints
97. PRIORITY HINTS ↝ INCREASE THE PRIORITY OF THE LCP IMAGE ↝ LOWER THE PRIORITY OF ABOVE-THE-FOLD IMAGES AND PRELOADED RESOURCES ↝ LOWER THE PRIORITY FOR NON-CRITICAL DATA FETCHES ↝ REPRIORITIZE SCRIPTS
98. PRIORITY HINTS < ! - - Increase the priority of the LCP image - - > <img src="image.jpg" fetchpriority="high" /> < ! - - Lower the priority of above-the-fold images - - > <ul class="carousel"> <img src="img/carousel-1.jpg" fetchpriority="high" /> <img src="img/carousel-2.jpg" fetchpriority="low" /> <img src="img/carousel-3.jpg" fetchpriority="low" /> </ul> < ! - - Reprioritize scripts - - > <script src="async_but_important.js" async fetchpriority="high"></script> <script src="blocking_but_unimportant.js" fetchpriority="low"></script>
99. PRIORITY HINTS < ! - - Increase the priority of the LCP image - - > <img src="image.jpg" fetchpriority="high" /> < ! - - Lower the priority of above-the-fold images - - > <ul class="carousel"> <img src="img/carousel-1.jpg" fetchpriority="high" /> <img src="img/carousel-2.jpg" fetchpriority="low" /> <img src="img/carousel-3.jpg" fetchpriority="low" /> </ul> < ! - - Reprioritize scripts - - > <script src="async_but_important.js" async fetchpriority="high"></script> <script src="blocking_but_unimportant.js" fetchpriority="low"></script>
100. PRIORITY HINTS / / Important validation data const user = await fetch("/user"); / / Less important content data const relatedPosts = await fetch("/posts/suggested", { priority: "low" });
101. PRIORITY HINTS / / Important validation data const user = await fetch("/user"); / / Less important content data const relatedPosts = await fetch("/posts/suggested", { priority: "low" });
102. WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED Responsive Images
103. RESPONSIVE IMAGES ↝ IMAGES FOR DESKTOP AND TABLET CAN BE ˜2-4X LARGER THAN THE MOBILE ONES. ↝ WITH srcset, THE BROWSER WON'T DOWNLOAD THE LARGER IMAGES UNLESS THEY'RE NEEDED. THAT SAVES BANDWIDTH.
104. RESPONSIVE IMAGES <img src="enterJS.png" srcset=" enterJS-300.png 300w, enterJS-600.png 600w, enterJS-1200.png 1200w " /> <img src="enterJS.png" srcset=" enterJS-1x.png 1x, enterJS-2x.png 2x, enterJS-3x.png 3x " />
105. RESPONSIVE IMAGES <img src="enterJS.png" srcset=" enterJS-300.png 300w, enterJS-600.png 600w, enterJS-1200.png 1200w " /> <img src="enterJS.png" srcset=" enterJS-1x.png 1x, enterJS-2x.png 2x, enterJS-3x.png 3x " />
106. WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED Native Lazy- Loading
107. NATIVE LAZY-LOADING <img src="image.png" loading="lazy" alt="…" width="200" height="200"> <iframe src="https://example.com" loading="lazy" width="600" height="400"></iframe>
108. NATIVE LAZY-LOADING <img src="image.png" loading="lazy" alt="…" width="200" height="200"> <iframe src="https://example.com" loading="lazy" width="600" height="400"></iframe>
109. #PROTIP 💡 Lazy-loading iframes can lead to 2-3% median data savings, 1-2% FCP reductions, and 2% FID improvements at the 95th percentile. — Chrome team’s research, 2019
110. WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED Native Scheduler
111. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
112. NATIVE SCHEDULER ↝ A MORE ROBUST SOLUTION FOR SCHEDULING TASKS ↝ CONTROL AND SCHEDULE PRIORITIZED TASKS IN A UNITED AND FLEXIBLE WAY ↝ INTEGRATED DIRECTLY INTO THE EVENT LOOP ↝ ALIGNED WITH THE WORK OF THE REACT TEAM AND IN COOPERATION WITH GOOGLE, W3C AND OTHERS
113. NATIVE SCHEDULER scheduler.postTask() SCHEDULE AND CONTROL PRIORITIZING TASKS. scheduler.wait() YIELD AND RESUME AFTER SOME AMOUNT OF TIME OR PERHAPS AFTER AN EVENT HAS OCCURRED. scheduler.yield() BREAK UP LONG TASKS BY YIELDING TO THE BROWSER AND CONTINUING AFTER BEING RESCHEDULED. isInputPending() DETERMINE IF THE CURRENT TASK IS BLOCKING INPUT EVENTS.
114. NATIVE SCHEDULER
116. …AND MUCH MORE! ↝ CSS TRICKS (E.G. font-display: swap AND will- change) ↝ IMPORT ON VISIBILITY (USING AN IntersectionObserver) ↝ CANVAS + WORKERS = OffscreenCanvas
117. …AND MUCH MORE! ↝ AVOID THE INITIAL HTTP TO HTTPS REDIRECTS SO THAT PAGES LOAD FASTER USING HTTP STRICT TRANSPORT SECURITY (HSTS) ↝ SEND DATA WITHOUT EXTRA ROUND TRIPS WITH QUIC
118. Move Fast & Break Nothing ™ WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED
119. BROWSER COMPATIBILITY PERFORMANCE OBSERVER USER TIMING LONG TASKS ELEMENT TIMING RESOURCE TIMING NAVIGATION TIMING
120. BROWSER COMPATIBILITY SERVER TIMING LAYOUT SHIFT JS SELF-PROFILING PAGE VISIBILITY BATTERY STATUS NETWORK INFORMATION
121. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
122. MOVE FAST & BREAK NOTHING ™ const Video = lazy(() = > import("./Video")); const Preview = lazy(() = > import("./Preview")); const networkInfo = useNetworkStatus(); const { With, Switch, Otherwise } = usePatternMatch(networkInfo);
123. MOVE FAST & BREAK NOTHING ™ <Suspense fallback={<div>Loading . . . </div>}> <With unsupported> <NetworkStatus networkInfo="unsupported" /> <Video /> </With> <With effectiveConnectionType="2g"> <NetworkStatus networkInfo="2g" /> <Preview /> </With> </Suspense>
124. NETWORK STATUS: NOT SUPPORTED
125. NETWORK STATUS: NOT SUPPORTED
126. NETWORK STATUS: 4G
127. NETWORK STATUS: 3G
128. NETWORK STATUS: CODE SPLITTING
129. NETWORK STATUS: CODE SPLITTING
130. Why are we here? WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED
131. WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED Browsers
132. WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED Which browsers are visiting our app? — APP DYNAMICS REPORT
133. BROWSER TOTAL — APP DYNAMICS REPORT
135. WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED Devices & Connection
136. #REALITYCHECK 😳 Phone users experience slow First Input Delay on 7x more websites. — Web Almanac By HTTP Archive, 2021
137. BANDWIDTH MIX — GSM ASSOCIATION, 2022
138. THE GLOBAL LTE PICTURE 6.07 (MBPS) 44.31 (MBPS) — THE STATE OF LTE BY OPEN SIGNAL, 2018
139. WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED People
140. British Psychology Society, 2009 40% of Brits reported that they had become physically violent toward their computers.
141. Radware, 2013 A 500ms delay resulted in up to a 26% increase in frustration and up to an 8% decrease in engagement.
142. Ericsson ConsumerLab, 2015 Delayed web pages caused a 38% rise in mobile users' heart rates — equivalent to the anxiety of watching a horror movie alone.
143. DoubleClick, 2020 53% of mobile users abandon sites that take over 3 seconds to load.
144. WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED Business
145. BUSINESS OUTCOMES — AKAMAI AND CHROME RESEARCH, 2017 ↝ LONG TASKS DELAYED TTI ↝ AS FIRST-PAGE LONG TASK TIME INCREASED, OVERALL CONVERSION RATES DECREASED ↝ MOBILE HAD UP TO ˜12X LONGER LONG TASKS ↝ OLDER DEVICES COULD BE SPENDING HALF OF THEIR LOAD-TIME ON LONG TASKS
146. BUSINESS OUTCOMES — AKAMAI AND CHROME RESEARCH, 2017
147. WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED Closing Notes
148. WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED ALWAYS TRY TO CORRELATE BUSINESS METRICS WITH PERFORMANCE. #1 of 6
149. WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED DON'T TAKE FAST NETWORKS, CPUS AND RAM FOR GRANTED. #2 of 6
150. WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED TEST ON REAL PHONES AND NETWORKS. #3 of 6
151. WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED AVOID THE OBSERVER EFFECT. #4 of 6
152. WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED GET RID OF THE NOISE IN YOUR METRICS. #5 of 6
153. WEB PERFORMANCE APIS THAT YOU (PROBABLY) NEVER KNEW EXISTED THERE'S NO SILVER BULLET. IDENTIFY YOUR CORE METRICS. #6 of 6
154. THAT’S ALL, FOLKS! THANKS! 👋 🇩🇪 QUESTIONS? MATHEUS ALBUQUERQUE • @ythecombinator ↑ ALL THE LINKS!